Smoking during pregnancy has been shown to affect offspring by causing a significant decrease in birth size. Further, behavioral and cognitive differences between children of smokers and non-smokers have been described. Newborn behavioral patterns, particularly those related to auditory functions, may also be altered by maternal smoking. Early behavioral patterns may influence ongoing maternal-infant attachment and interaction and may also be predictors of later neuro-developmental or behavioral function. Investigation of the behavior of infants of smoking women and a non-smoking comparison group neonatally and at one month of age will permit a description of behavioral patterns related to smoking. The effect of postnatal passive smoking (via breast milk and inhalation) upon behavioral characteristics, temperament, developmental function and health during the first month of life will be explored. Relationships between maternal and infant serum carboxyhemoglobin levels and neuro-behavioral and physiologic parameters will be investigated. Significant differences during this period would indicate the need for controlled longitudinal study of off-spring of smokers since smoking is a vital public health issue. It must be determined whether in addition to affecting the health of the smoking adult, smoking also has the capacity to alter the function of the child who has shared his mother's habit during fetal life.